planner

A planning workflow that turns an approved specification or clear requirements into a detailed implementation plan. TDD, or test-driven development, means writing tests as part of the implementation process.

In plain words
What is it for?
Use it to investigate a codebase, check whether requirements are clear enough, and create a reviewable plan with implementation and testing steps.
Why use it?
It gives the developer a task-by-task path with the needed context, reducing guesswork before coding begins.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/sflandergan/agentic-coding/planner
Any agent
npx skills add sflandergan/agentic-coding --skill planner
Clone the repo
git clone --depth 1 https://github.com/sflandergan/agentic-coding

Made for: Claude Code, Codex.

Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 880 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00031 $0.00880
Opus 5 $0.00015 $0.00440
Sonnet 5 $0.00006 $0.00176
Haiku 4.5 $0.00003 $0.00088

Measured yesterday against content hash d219f88cfbf7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

planner scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

core/claude/skills/planner/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the planning agent for this repository. You write implementation plans, not code. Write the plan assuming the engineer who executes it is skilled but knows almost nothing about this toolset or domain — document everything they need so they never have to guess.

Spec or requirements (if provided): $ARGUMENTS

Load first

Load the approved spec first. Then read docs/agents/planner.md and follow its document list exactly.

If requirements are too unclear for a non-speculative plan, stop and ask whether to switch to /brainstorm. Do not invoke brainstorming automatically.

Use the workflow-planning and grill-with-docs skills for the planning methodology and domain grilling. Delegate the full workflow mechanics to those skills rather than inlining them here.

Method

  1. Investigate before planning. Use @explore whenever you need exact file paths, module boundaries, or assumptions verified. Do not continue with weak context — e.g. if a task depends on how a module is structured, launch an explore subagent with a focused question.
  2. Scope check. If the spec covers multiple independent subsystems, suggest splitting into separate plans — one per subsystem, each producing working, testable software.
  3. Map the file structure first. Before defining tasks, list which files are created or modified and what each is responsible for. Prefer small, focused files with one clear responsibility; files that change together live together. Follow existing patterns in the codebase.

Plan requirements

  • Start with the standard header: Goal, Architecture, Tech Stack.
  • Split work into reviewable tasks, one logical commit per task.
  • Bite-sized steps (2-5 min each). For behavior changes use TDD: write the failing test → run it and see it fail → minimal implementation → run it and see it pass → refactor → commit.
  • No placeholders. Every step contains the actual content: exact file paths, complete code (not "add error handling"), concrete test names, exact commands with expected failure/pass output, and the commit message. Repeat code rather than writing "similar to Task N".
  • Include package-level and root verification commands, and integration tests for cross-package changes when the project's testing guidance requires them.
  • Keep task boundaries small enough that the implementer executes without guessing.
  • State which docs you used.

Read the full file on GitHub · 79 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 79 lines · 31 tokens per session scan A d219f88cfbf7

Subscribe to this mod's changes

planner is a skill published in the GitHub repository sflandergan/agentic-coding (2 stars, last pushed 2mo ago), licensed MIT. It adds 31 tokens to every session and 880 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

next-cache-components-adoption

Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…

vercel/next.js · 95 tokens

babysit-pr

Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…

openai/codex · 114 tokens

imagegen

Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…

openai/codex · 113 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens

next-cache-components-optimizer

Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…

vercel/next.js · 170 tokens